This invention relates to prosthetic valves which might find application as prosthetic aortic valves for percutaneous insertion and placement within a fluid passageway of a living body.
One example of a prosthetic valve is that of an aortic heart valve controlling blood flow from the heart within the human body. Occasionally valve failure will occur as a result of disease, wherein a heart valve becomes incompetent. During the pumping action of the heart, blood either regurgitates or leaks back across the incompetent valve against the normal direction of blood flow. This type of valve failure results in a decrease in heart pumping efficiency, the heart having to work harder to pump the required blood flow. Therefore, prosthetic valves have been developed and are manufactured which replace diseased or incompetent natural valves of the heart.
Replacement of heart valves with prosthetic valves within the human body was perhaps first documented by Hufnagel in 1954. Hufnagel C. A. Harvey W. P. Rabil P. J. McDermott R. F.: Surgical Correction of Aortic Insufficiency, Surgery, 35:673, 1954. Since then numerous prosthetic valves have been developed, including both mechanical and biological heart valves. Mechanical heart valves are generally of two designs, either a ball-in-cage valve or a disc valve. One example of a mechanical heart valve is that of Boretos, U.S. Pat. No. 3,911,502, which describes a composite heart valve poppet for use with ball-in-cage artificial heart valves. The poppet includes a core of rigid material covered by an elastomer jacket. Leibinsohn, U.S. Pat. No. 3,626,518, discloses an artificial cardiac valve having characteristics of both a ball valve and a disc valve for improved streamlined blood flow and reduced turbulence. Hamaker, U.S. Pat. No. 3,574,865, discloses a prosthetic sutureless heart valve, the heart valve fastening to the heart via a two-piece snap ring. Somyk, U.S. Pat. No. 3,857,815, discloses a suture ring for a heart valve, wherein a cylindrical collar extends radially from the valve to facilitate attachment.
With regard to currently available prosthetic valves, the physician/patient must weigh the advantages and disadvantages of each type of prosthetic valve. However, no choice currently exists regarding the installation and placement of the prosthetic heart valve. Currently, installation of prosthetic valves requires general anesthesia and open-heart surgery. As a result, the recipient of the prosthetic valve is subjected to the inherent risk of mortality associated with surgery. Therefore, a major factor when deciding whether to replace a valve and choosing the type of prosthetic valve is the mortality risk associated with the surgery. Furthermore, because biological valves have a limited useful life and thrombosis can lead to obstruction of the mechanical valve, repeat surgeries may be required to maintain the valve which further increase the mortality risk to the patient.
A need therefore exists for a prosthetic heart valve which does not require surgery for installation and placement and, therefore, avoids the mortality risk associated with surgery. Such a valve would provide treatment for an incompetent valve and the aortic regurgitation resulting therefrom without requiring general anesthesia and open-heart surgery. Ideally, such a valve would be placed in a fluid passageway via transcatheter techniques, similar to that currently used for the installation and placement of endovascular stents.